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authorJohn Naylor <john.naylor@postgresql.org>2025-03-07 10:22:56 +0700
committerJohn Naylor <john.naylor@postgresql.org>2025-03-07 10:25:02 +0700
commitbc6a81ac3a8346c9f3cb5fc6f714977127aa2f31 (patch)
tree8c97bcbf9fad83a9761b7f3f702a7c24476ef7da
parent2d313375c092d5bbe67539bfa3c1630808339f89 (diff)
Doc: correct aggressive vacuum threshold for multixact members storage
The threshold is two billion members, which was interpreted as 2GB in the documentation. Fix to reflect that each member takes up five bytes, which translates to about 10GB. This is not exact, because of page boundaries. While at it, mention the maximum size 20GB. This has been wrong since commit c552e171d16e, so backpatch to version 14. Author: Alex Friedman <alexf01@gmail.com> Reviewed-by: Sami Imseih <samimseih@gmail.com> Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com> Discussion: https://postgr.es/m/CACbFw60UOk6fCC02KsyT3OfU9Dnuq5roYxdw2aFisiN_p1L0bg@mail.gmail.com Backpatch-through: 14
-rw-r--r--doc/src/sgml/maintenance.sgml5
1 files changed, 3 insertions, 2 deletions
diff --git a/doc/src/sgml/maintenance.sgml b/doc/src/sgml/maintenance.sgml
index 3e999740a71..90237058af0 100644
--- a/doc/src/sgml/maintenance.sgml
+++ b/doc/src/sgml/maintenance.sgml
@@ -791,10 +791,11 @@ HINT: Stop the postmaster and vacuum that database in single-user mode.
As a safety device, an aggressive vacuum scan will
occur for any table whose multixact-age is greater than <xref
linkend="guc-autovacuum-multixact-freeze-max-age"/>. Also, if the
- storage occupied by multixacts members exceeds 2GB, aggressive vacuum
+ storage occupied by multixacts members exceeds about 10GB, aggressive vacuum
scans will occur more often for all tables, starting with those that
have the oldest multixact-age. Both of these kinds of aggressive
- scans will occur even if autovacuum is nominally disabled.
+ scans will occur even if autovacuum is nominally disabled. The members storage
+ area can grow up to about 20GB before reaching wraparound.
</para>
<para>